1. Field of the Invention
This invention relates to magnetic recording and playback heads and, in particular, to playback heads utilizing a magnetoresistive transducer element.
2. Description of the Prior Art
Magnetoresistive (MR) playback heads are now well known in the art, having been perhaps first described in U.S. Pat. No. 3,493,694 (Hunt), and subsequently improved and elaborated upon in a number of respects. Thus, for example, as described in U.S. Pat. No. 3,881,190, magnetoresistive head constructions are now well known in which a bias field is provided by including a conductive layer adjacent to the magnetoresistive layer, current flowing through the conductive layer producing a magnetic field which biases the MR element to produce a more linear response. The '190 patent further discloses the desirability of sandwiching the MR element between magnetic shielding layers to enable the use of an extended throat height in the MR element, thus providing a structure useful for short wavelength recording. Numerous variants of such constructions have subsequently been disclosed. One such variant employs a ferrite as the substrate on which successive thin films of insulators, MR elements, bias conductors, additional shield layers, etc., may be deposited, the ferrite shield thus intrinsically acting as a one shield element. It is also known to provide an additional MR layer functioning to carry a current to bias the operation of an adjacent MR layer.